I still think NPD should release PC sales figures- as long as it's made clear that they're just boxed retail, then I don't see any harm in doing so. Could VGChartz do the same as well? If they're collecting figures from a sample of various outlets that also sell PC games, it would be pretty trivial to also quote them along with the console numbers.
BTW, does anybody have an idea of the sort of sales that Steam generates? It apparently has over 15 million users, but Valve have never released any figures. Doug Lombardi stated recently that total revenues from Steam over the last 4 years or so would soon surpass combined retail revenues from Valve's games, so it must be a healthy amount. Would anyone care to hazard a guess as to what the likes of COD4, Bioshock, Audiosurf and the like have sold through Steam?







